Many hydrocarbon producing wellbores have several different spaced apart production zones located a substantial distance apart from one another. Production simultaneously occurs from each of the zones and sometime it is discovered that one of the zones is not producing sufficient production fluid. Accordingly, the well is treated by isolating the suspected poor production zone and pumping acid and proping agents down the wellbore and through the perforations of the casing. Often the treated formation does not favorably respond to the chemical treatment because the treatment fluids have flowed up or down the borehole annulus rather than laterally away from the borehole and back up into the desired formation.
Sometimes the undesired flow path by which the treatment fluid flows up or downhole is closed by packing off the faulty zone and squeezing cement into the perforations, whereupon the formation must again be perforated in order to re-establish communication between the borehole and the hydrocarbon containing formation. This operation is not always successful for it does not always eliminate the cause for the loss or misplacement of the treatment fluid.
The above treatment, cement squeeze operation, and retreatment of the pay zone is very costly and often leads to the erroneous assumption that the pay is inadequate for continued production and therefore sometimes results in the loss of a considerable quantity of hydrocarbons. Overcoming the above problems is the subject of this invention.
In secondary recovery processes, injection wells are radially spaced from production wells so that water can be pumped downhole into the hydrocarbon-bearing formations in a manner which forces some of the remaining hydrocarbons radially from the injection wells and in a direction towards the production wells.
In some geographical locations, the injected water flows from the water injection well to a production well whereupon the water then flows uphole or downhole, whereupon the water becomes lost by flowing into a cavity or another formation. The water usually flows longitudinally along the casing as a result of a poor cementing job, or because of the presence of salt deposits which are solubilized by the water, thereby forming a passageway which leads to a water-accepting area. It is difficult to perforate and squeeze such a passageway in order to repair the resultant damage caused by the poor cement job because the velocity of the water flowing through the washed-out passageways or tunnels make such an operation unsuccessful. Overcoming the above problem is another subject of this invention.